The present invention relates to novel polymer compositions useful in reversibly complexing with gases such as oxygen, hydrogen, sulfur dioxide, alkenes, carbon monoxide and the like. The present invention further comprehends a novel method by which the polymer compositions can be synthesized.
It is known that certain metal complexes take up gases to form adducts from which the gases can be recovered. The Cobalt (II) complex known as the Salen Chelate and related Fluomine chelate complexes of the Vaska type, in which the metal is iridium, ruthenium, osmium or rhodium, take up oxygen reversibly. Under moderate conditions the adducts do not however release oxygen to regenerate the sorbent complexes sufficiently readily to enable oxygen to be produced or nitrogen to be purified on a commercial scale.
It is also known that certain chemical complexes will reversibly complex with gases. In particular McAuliffe et al, in the U.S. Pat. No. 4,251,452 disclose and claim certain manganese-tertiary phosphine complexes useful in the separation of a gas such as oxygen, hydrogen, sulfur dioxide, alkenes and carbon monoxide from a fluid comprising the gas.
The compositions disclosed and claimed by McAuliffe et al. are of the formula: EQU MnLX.sub.2
in which X is a species capable of existing as an anion and L represents a monodentate ligand of formula: EQU PR.sup.1 R.sup.2 R.sup.3
wherein R.sup.1, R.sup.2, and R.sup.3 may be the same or different and represent substituted or unsubstituted alkyl, cycloalkyl or aryl groups or hydrogen provided that no more than two of the groups R.sup.1, R.sup.2, and R.sup.3 are substituted or unsubstituted aryl groups and that at least one of the groups R.sup.1, R.sup.2, and R.sup.3 is a substituted or unsubstituted alkyl, cycloalkyl or aryl group. X is preferably --Cl, --Br, --I, --CN, --NO.sub.2, --NO.sub.3, --OH, --NCS or --NCO.
McAuliffe et al. speculate that their manganese complexes may in fact exist in dimeric or tetrameric form in which case: EQU MnLX.sub.2
is the empirical formula.
McAuliffe et al. contemplate use of their compositions either in liquid solution, or carried on a particulate support. Each of these application techniques has substantial drawbacks, and in the particulate solid case the rate of gas absorption or desorption is relatively slow. Attempts to incorporate the compositions of McAuliffe et al. into polymers, or liquid polymer solutions, did not provide acceptable compositions for use in reversible complexing. When cast as a film the polymer composition would absorb gas, but would not reversibly release the gas.
For example a tri-n-butyl phosphine manganese (II) thiocyanate complex, a composition taught by McAuliffe, was incorporated into a 10% solution of polyvinylchloride in tetrahydrofuran. When a film was cast from the solution, the resulting film absorbed oxygen as evidenced by a change in color intensity, but did not release oxygen when the oxygen content of the ambient gaseous atmosphere was subsequently reduced.